Combustion engine with rotary piston arrangement

ABSTRACT

In a combustion engine having a rotary-type piston mounted for rotation and having a cross sectional area defining a trochoid, an outer housing receiving the piston and being in meshing engagement therewith, the housing having an inner surface which has a cross sectional shape representing the envelope of a trochoid curve and forms a plurality of housing arches which include the combustion chambers in the form of recesses, each chamber being arranged to fall in the half of a housing arch which is first swept by the piston during the relative movement between the housing and the piston.

United States Patent [191 Hofbauer COMBUSTION ENGINE WITH ROTARY PISTONARRANGEMENT [75] Inventor: Peter Holbluer, Wolfsburg, Germany [73]Assignee: Volkswagenwerk AG, Wolfsburg,

Germany [22] Filed: Oct. 6, 1971 [21] Appl. No.: 186,914

30 Foreign Application Priority um [56] References Cited UNITED STATESPATENTS 3,289,646 12/1966 Peras .L ..l23/8.13

[451 Aug. 28, 1973 3,358,439 12/1967 Caste1et.., 123/805 2,893,3607/1959 Muller 123/32 Primary Examiner-Clarence R. Gordon Attorney-ErnestF. Marmorek [57] ABSTRACT In a combustion engine having a rotary-typepiston mounted for rotation and having a cross sectional area defining atrochoid, an outer housing receiving the piston and being in meshingengagement therewith, the housing having an inner surface which has across sectional shape representing the envelope of a trochoid curve andforms a plurality of housing arches which include the combustionchambers in the form of recesses, each chamber being arranged to fall inthe half of a housing arch which is first swept by the piston during therelative movement between the housing and the piston.

14 Claims, 5 Drawing Figures SHEEI '1 [If 2 PAIENTEU M28 878 Fig. 7

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QM J-lis AHo'rney COMBUSTION ENGINE ,WITI-I ROTARY PISTON ARRANGEMENTFIELD OF THE INVENTION The present invention relates to a combustionengine having a rotary piston in general, and more particularly itrelates to a combustion engine having apiston of the section of atrochoid-shapc and wherein an outer housing or cover comes into meshingengagement with the piston, the inner surface of the outer cover havinga cross section of the envelope curve of a trochoid and forms housingarches in which the combustion chambers are provided in the form ofrecesses.

BACKGROUND OF THE INVENTION It became known in connection withcombustion engines having a rotary-type piston of the above de scribedtype to arrange the combustion chambers in an off-set fashion in theform of recesses in the housing arches. Such combustion chamberconstruction is described in German laid-open publications 1,576,202 and1,576,203.

The reason for such an arrangement according to laid-out publication1,576,203 is to improve the combustion process by the regulation of theair movement. For this reason the inlet channel when viewed in thedirection of the rotation of the piston is upstream or forwardlydirected into the combustion chamber in order that each time the inletcontrol opening becomes connected to the chamber the fresh mixtureenters the transversely running combustion space in a tangential fashionand after further rotation of the piston it will excite the edge zone ofthe circulating air inthe combustion space and and increases the createdturbulence the axis of which is substantially parallel with the axis ofthe machine. This affect becomes further increased by the shifting ofthe combustion chamber to the back half of the outer arch of the coverwhen viewed in the direction of rotation of the piston and also into aportion of the cover which is swept by the piston at the last instance.At this momentum producing system the channels in the piston arearranged in a manner which is advantageous to the supply efficiencysince the fact that the inlet channels terminate in the combustionchamber forwardly or in an upstream fashion when viewed in the directionof the rotation of the piston causes a slight weight of flow and highflow losses. The desire is to attain a high kinetic energy which.however, at the time instant of the ignition has fallen to aboutcircularly displaced type in which the piston has a cross I the chargemovement so that it is capable of providing a high supply efficiency.

It is another object of the present invention to provide the improvedcombustion engine having a rotary type piston therein in which thepressure peak during the combustion process will impart in thecombustion chamber to the piston a positive rotational momentum even atthe upper dead point of the piston.

According to the present invention the combustion chamber lies in thehalf of the housing arch which during the relative movement between thehousing and the piston becomes first swept by the piston. The inlet isvprovided when viewed in the direction of the rotation of the pistondownstream or in the back and terminates into the combustion chamber. Asa result of such structuring of the inlet a high supply efficiency canbe attained. The movement of the charge becomes during the compressioncycle very favorably improved by the pushing effect. The portion of thepiston which performs the compression runs next into the portion of thehousing arch in which the combustion chamber lies and forms with thehousing arch a nozzle-like inlet for the combustion chamber while stilla considerable portion of the gas is undergoing compression in the otherportion. This portion of the fresh gas or mixture becomes by thearrangement of the combustion chamber only during the last part ofthe'compression cycle especially strongly forced into the combustionchamber and thereby very high rotational energies are produced which inturn bring about an extremely fine eddyingjor turbulence in theneighborhood of the ignition instant. The maximum of the rotationalenergy takes place at the ignition time.

In order to further increase the turbulence the combustion chamberbecomes constructed in a roller-shape having an axis which lies parallelwith respect to the axis of the excentric shaft of the piston. Thecombustion chamber is provided at least at its frontal transition to thehousing arch with a small radius which in its exact dimensions dependson the thermal load in order to increase the nozzle effect and therebythe creation of the fine eddying turbulence at the beginning part ofone-fourth of its original value. The fact which influ- SUMMARY OF THEINVENTION It is, therefore an object of the present invention, toprovide an improved combustion engine having a rotary type pistontherein wherein directly before and,

during the: combustion process a considerable charge rotation havingfine eddying-turbulences therein is-produced without effecting thesupply efi'iciency, with an improved structuring. of'the inlet channelin relation to the combustion chamber. The sparkplug is providedvapproximately in the region of the axis of the rollershaped combustionchamber.

In accordance with a further feature of the present invention thecombustion chamber will create a layer charge and the combustion chamberby means of a reduction or neck portion is subdivided into an antechamber and into a main combustion chamber surrounded by the housingarch and opening into the operating chamber. In the ante-chamber inwhich the spark;- plug is placed an additional amount of fuel isinjected. The main combustion space remains with respect to theoperating chamber open and becomes supplied with a relatively leanmixture through the inlet channel provided in the piston. The mixture init can be ignited for example by means of a torch ignition process fromthe ante-chamber (internal mixture formation). As a furthersimplification and ,in another embodiment the ante-chamber is alsoconstructed open with respect: to

The resultant of the driving forces directly after the ignition,operates as a result of the arrangement of the combustion chamberaccording to the present invention, at the mid point of the piston andthereby it creates even at the upper dead point a positive rotationalmomentum. As a result a better uniformity and an improved efficiency ofthe engine is obtained. In contrast to this in the combustion chamber ofthe known arrangement a negative rotational momentum is created in themid point or after the mid point when viewed in the rotation of thepiston in the back half of the housing arch at the upper dead point.

A further considerable advantage of the present invention resides inthat during the compression cycle the relatively cold fresh mixture whencompared with the piston surface will sweep over the hot zones of thepiston at a high speed and thereby at a high heat transfer coefficientand, as a result, it cools the piston and, simultaneously contributes tothe improvement of the efficiency.

This becomes possible when the engine is constructed according to thepresent invention and even if the Otto method is used since the dangerof knocking will not be present even in the case of extreme turbulences.In contrast to this in the known construction of the combustion chamberthe hot portions of the piston which lie across the combustion chamberin the region of the upper dead point are running already in the firstpart of the expansion stroke under the next radial sealing means intothe next chamber and do not contribute anymore to the hydrocarbonoxydation. The radial sealing means are thereby exposed to a highthermal load.

In the engine according to the present invention and, in general inengines of this type the kinematically defined dead space is very small.This fact permits a free selection of the combustion chamber especiallythen when the mixture control is performed by means of slots in thepiston. In connection with this, the combustion chamber according to thepresent invention is capable of bringing about a layer charge. By meansof such layer charge the use of the diesel method becomes possible inwhich obviously the sparkplug is omitted and the inlet in the pistonwill feed pure air.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more readilyapparent from the following description of preferred embodiments thereofshown in the accompanying drawings, in which:

FIG. 1 is a partial cross-sectional view of a planetary or rotary typemotor with Ka :4;

FIG. 2 is a diagramatic comparison of the turbulent energies of theknown engines and of the engine according to the present invention.

FIGS. 3-5 are different embodiments for the combustion chambers to bringabout a layer charge.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1 it isseen that in a motor housing 1 a piston 3 is rotated on an excentershaft 2 in the direction as indicated by the arrow. The housing 1 in itscross sectional showing has the form of the envelope curve of atrochoid. The piston 3 having also in its cross section a trochoid shapeis in meshing engagement with the housing. The combustion space 5 is inthe shape of a roller the axis of which lies parallel to the axis of theexcentric shaft 2. In the axis of the combustion chamber 5 a sparkplug 6is arranged which, however, also can be placed vertically with respectto such axis. The front edge 7 of the combustion chamber is rounded offwhile the other front edge 8 of the combustion chamber 5 is formed withsharp edges. The operating space 9 is limited at one side by the housingarch 4 and on the other side by the radial sealing means 10. Thereference numeral 11 identifies the inlet openings running against thedirection of the rotation of the piston 3 while the reference numeral 12identifies the outlet openings. It would be also possible to providesealing means 14 also at the mouth 13 of the combustion chamber 5 formedwith the operating space 9 which would have the purpose to furtherincrease the turbulences when the mixtures are pushed over into thecombustion space 5 and in order to longer sustain the positiverotational momentum at the upper dead point.

The operation of the arrangement according to the present inventionbecomes easily understood on hand of the figures. The piston 3 deliversby means of the inlet opening 1 l a high mass of fresh mixture. Themovement of the charge is forced then during the further compressioncycle by the pushing effect of the piston 3. The part of the pistonwhich performs the compression runs mainly in the part of the operatingspace 9 which contains the combustion chamber 5 and forms with thehousing arch 4 a nozzle-like entry 15 which is further improved by thefront sharp edge 8 of the combustion chamber 5 while a considerable partof the fresh mixture becomes further compressed in the part 20 of theoperating space 9. This fresh mixture mass becomes first shoved in thelast part of the compression cycle at high speed in the combustionchamber 5 and produces thereby at the instant of the ignition a veryfine eddying turbulence. The preliminary sealing means 14 aids to longersustain the pressure in the combustion chamber 5.

FIG. 2 illustrates a comparison in a diagramatic form of the turbulenceenergies produced by the compression cycle in the known machines and inthe engines according to the present invention. The abscissa trepresents the angle of rotation measured from the upper dead point OTover the lower dead point UT and back to the upper dead point OT whilethe ordinate E represents the kinetic energy of gases within theoperating space 9. The dashed line 16 illustrates the energy process ina known machine and from such curve 16 can be easily seen than thehighest energy andconsequently the fine eddying turbulence is attainedalready long before the attainment of the ignition instant ZZP and,thereafter it falls very steeply. The curve 17 illustrates theturbulence energy process in an engine according to the presentinvention. The highest kinetic energy is attained approximately at thepoint 18 which is the time instant of the ignition ZZP.

FIGS. 3-6 illustrate the different embodiments of the combustionchambers which are identified by the reference numeral 5 in FIG. 1 andwhich contribute to the creation of a layer charge according to thepresent invention. The sparkplug 6 is arranged as shown in FIGS. 35 andthe reference numeral 19 identifies an additional injection inlet suchas in the case of a diesel engine the injection nozzles represent. Thereference numeral 20 identifies the fuel and the reference numeral 21identifies a stream which has been branched off therefrom. The neckportion 24 between the main combustion chamber 25 and the ante-chamber23, as seen in FIG. 4, is constructed in such a manner that the stream21 is directed to the sparkplug 6 in a straight line.

The reference numeral 22 identifies a side portion of the engine. Adetailed description of the operation of the engine highlighting theoperation of the sparkplugs and of the injection openings is believed tobe unnecessary.

The dimensional relationship of the ante-chamber 23 and the maincombustion chamber 25 can be varied and is not limited to theillustrated dimensional showing of the figures.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described, for obviousmodifications will occur to a person skilled in the art.

Having thus described the invention, what I claim as new and desire tobe secured by Letters Patent, is as follows:

1. In a combustion engine, a rotary-type piston mounted for rotationtherein, said piston having a cross-sectional area defining a trochoid,an outer housing receiving said piston means and being in meshingengagement with said piston means, said housing having an inner surfacehaving a cross sectional shape representing the envelope of a trochoidand forms a plurality of housing arches, each of said housing archescomprising a combustion chamber in the form of recess, said combustionchamber being arranged in the half of the respective housing arch whichis first swept by said piston means during the relative movement betweensaid housing and said piston means.

2. The combination as claimed in claim 1, wherein said combustionchamber is in the shape of a cylinder having an axis lying parallel tothe axis about which said piston means rotates, said piston means beingrotated about an excenter shaft.

3. The combination as claimed in claim 1, wherein each of saidcombustion chambers has a first transition part with said housing arch,said first transition part being formed with a small radius.

4. The combination as claimed in claim 2, wherein said combustionchamber comprises a sparkplug means arranged approximately in the axisof said combustion chamber.

5. The combination as claimed in claim 1, wherein said combustionchamber is subdivided into an antechamber and into a main combustionchamber, said main combustion chamber opening into an operating space ofthe engine, said main combustion chamber of the engine being defined bysaid housing.

6. The combination as claimed in claim 5, wherein said ante-chambercommunicates with said main operating space of the engine.

7. The combination as claimed in claim 5, wherein said sparkplug meansbeing provided in said ante chamber and a fuel inlet means providing fora layering of the fuel within said combustion chamber, whereby a portionof said injected fuel is directed to the sparkplug in said ante chamberand the main portion of said fuel is directed into said main combustionchamber.

8. In a motor vehicle, a combustion engine having a rotary-type pistonmounted for rotation therein, said piston having a cross-sectional areadefining a trochoid, an outer housing receiving said piston means andbeing in meshing engagement with said piston means, said housing havingan inner surface having a cross sectional shape representing theenvelope of a trochoid and forms a plurality of housing arches, each ofsaid housing arches comprising a combustion chamber in the form ofrecess, said combustion chamber being arranged in the half of arespective housing arch which is first swept by said piston means duringthe relative movement between said housing and said piston means.

9. The combination as claimed in claim 8, wherein said combustionchamber is in the shape of a cylinder having an axis lying paralleltothe axis about which said piston means rotates, said piston means beingrotated about an excenter shaft.

10. The combination as claimed in claim 8, wherein each of saidcombustion chambers has a first transition part with said housing arch,said first transition part being formed with a small radius.

11. The combination as claimed in claim 9, wherein said combustionchamber comprises a sparkplug means arranged approximately in the axisof said combustion chamber.

12. The combination as claimed in claim 8, wherein said combustionchamber is subdivided into an antechamber and into a main combustionchamber, said main combustion chamber opening into an operating space ofthe engine, said main combustion chamber of the engine being defined bysaid housing a'rch.

13. The combination as claimed in claim 12, wherein said ante-chambercommunicates with said main operating space of the engine.

14. The combination as claimed in claim 12, wherein said sparkplug meansbeing provided in said ante chamber and a fuel inlet means providing fora layering of the fuel within said combustion chamber, whereby aportionof said injected fuel is directed to the sparkplug in said antechamber and the main portion of said fuel is directed into said maincombustion chamber.

1. In a combustion engine, a rotary-type piston mounted for rotationtherein, said piston having a cross-sectional area defining a trochoid,an outer housing receiving said piston means and being in meshingengagement with said piston means, said housing having an inner surfacehaving a cross sectional shape representing the envelope of a trochoidand forms a plurality of housing arches, each of said housing archescomprising a combustion chamber in the form of recess, said combUstionchamber being arranged in the half of the respective housing arch whichis first swept by said piston means during the relative movement betweensaid housing and said piston means.
 2. The combination as claimed inclaim 1, wherein said combustion chamber is in the shape of a cylinderhaving an axis lying parallel to the axis about which said piston meansrotates, said piston means being rotated about an excenter shaft.
 3. Thecombination as claimed in claim 1, wherein each of said combustionchambers has a first transition part with said housing arch, said firsttransition part being formed with a small radius.
 4. The combination asclaimed in claim 2, wherein said combustion chamber comprises asparkplug means arranged approximately in the axis of said combustionchamber.
 5. The combination as claimed in claim 1, wherein saidcombustion chamber is subdivided into an ante-chamber and into a maincombustion chamber, said main combustion chamber opening into anoperating space of the engine, said main combustion chamber of theengine being defined by said housing.
 6. The combination as claimed inclaim 5, wherein said ante-chamber communicates with said main operatingspace of the engine.
 7. The combination as claimed in claim 5, whereinsaid sparkplug means being provided in said ante chamber and a fuelinlet means providing for a layering of the fuel within said combustionchamber, whereby a portion of said injected fuel is directed to thesparkplug in said ante chamber and the main portion of said fuel isdirected into said main combustion chamber.
 8. In a motor vehicle, acombustion engine having a rotary-type piston mounted for rotationtherein, said piston having a cross-sectional area defining a trochoid,an outer housing receiving said piston means and being in meshingengagement with said piston means, said housing having an inner surfacehaving a cross sectional shape representing the envelope of a trochoidand forms a plurality of housing arches, each of said housing archescomprising a combustion chamber in the form of recess, said combustionchamber being arranged in the half of a respective housing arch which isfirst swept by said piston means during the relative movement betweensaid housing and said piston means.
 9. The combination as claimed inclaim 8, wherein said combustion chamber is in the shape of a cylinderhaving an axis lying parallel to the axis about which said piston meansrotates, said piston means being rotated about an excenter shaft. 10.The combination as claimed in claim 8, wherein each of said combustionchambers has a first transition part with said housing arch, said firsttransition part being formed with a small radius.
 11. The combination asclaimed in claim 9, wherein said combustion chamber comprises asparkplug means arranged approximately in the axis of said combustionchamber.
 12. The combination as claimed in claim 8, wherein saidcombustion chamber is subdivided into an ante-chamber and into a maincombustion chamber, said main combustion chamber opening into anoperating space of the engine, said main combustion chamber of theengine being defined by said housing arch.
 13. The combination asclaimed in claim 12, wherein said ante-chamber communicates with saidmain operating space of the engine.
 14. The combination as claimed inclaim 12, wherein said sparkplug means being provided in said antechamber and a fuel inlet means providing for a layering of the fuelwithin said combustion chamber, whereby a portion of said injected fuelis directed to the sparkplug in said ante chamber and the main portionof said fuel is directed into said main combustion chamber.